The Effect of Mirthful Laughter on the Human Cardiovascular System
Written by Michael Miller, M. D. and William F. Fry, M. D.
Laughter is a complex human behavior, with inherent characteristics involving and reflecting participation of almost every functional element of the human organism. Laughter is ubiquitous in the human world population. No human group has been identified as being devoid of laughter.
Psychologically, there are many different types of laughter. Some types are unifying, enhancing rapport and understanding, augmenting communication, and contributing to good will and harmony. Other types of laughter may be viewed as divisive with inherent anti-social properties. The most frequent, most widely recognized and most culturally congenial of all laughter types is that associated with Humor. It is specified as mirthful laughter.
Mirthful laughter is composed of active involvements with many different factors of human biologic functioning, preeminently the respiratory and muscular systems. That axiom arises in large part from formal scientific consideration of the physiologic nature of this active, dynamic process.
During the past century, general research in human physiology has demonstrated extensive and complex inter-relationships between respiratory activities and functioning of the cardiovascular system. Considerable efforts have delineated details of reciprocal influences between pulmonary functioning (with neuromuscular participation) and blood pressure regulation. It is not scientifically surprising to discover that in many ways these functional networks perform in intricate coordination. That coordination has been demonstrated to be naturally achieved and maintained through biological events mediated by a very busy and very profuse array of monitors and other bio-cybernetic controls, operating according to basic chemical and physical principles (5).
The intensity and complexity of this coordinated respiratory/circulatory network is observed to be wholly consistent with the survival issues of the biologic functions under those controls. That consistency is found in consideration of the inter-relationship of specific respiratory activity (in this case, mirthful laughter) and in vivo arterial blood pressure. Further, parallel consistency of these research findings is observed when results of experimentation with mirthful laughter are matched with results obtained in studies of blood pressure effects of other respiratory-determined behavior - e.g., coughing, talking (6-10).
However, at this point, a larger inconsistency appears and makes it necessary to question the evolutionary logic of this schema. We are forced to question the survival prospects for a creature that is susceptible to damaging, or even destroying the integrity of its vital oxygenation/circulation apparatus at any time that an indiscretion of frequent emotive behavior exceeds relevant tissue threshold.
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